Urine Testing

Testing Urine Unit 18:11

Urinalysis Examination of urine Physical Chemical Microscopic

Physical Testing of Urine Observing color, transparency & specific gravity

Color Normal: shade of yellow Pale: dilute Dark yellow, orange: concentrated Cloudy red: hematuria Clear-red: hemoglobin Yellow or beer-brown: bilirubin (bilirubinuria)

Transparency Normal: clear Cloudy: pus, mucus Milky: fats

Specific Gravity Normal: 1.005 to 1.030 Increased: dehydration, diabetes mellitus Decreased: kidney disease, diuretic, increased fluid intake

Odor Normal: Faintly aromatic Ammonia: old sample Foul: infection Sweet: DM, ketones

Chemical Testing pH Protein Glucose Ketones Bilirubin Urobilinogen Blood

Microscopic Testing Examine formed elements in urine Cells Casts Crystals Amorphous debris

Which urine is best? Fresh, warm urine Within 1 hour of collection Maybe refrigerated if needed

Precautions Must use standard precautions Gloves, possibly mask, eyewear Discard urine in a toilet Dispose of specimen in infectious waste bag

Using Reagent Strips to Test Urine Unit 18:12

Reagent Strips Firm plastic strip with chemical reactants attached to the strip Color change indicates presence of substance & amount of substance

Storage Sensitive to light, heat, moisture Store in dry, cool, dark area Keep bottle closed

Precautions Don’t touch chemical reactant pads May lead to inaccurate results or injure the skin

pH Measure of acidity or alkalinity of urine Normal: 5.5 to 8.0 Affected by: Diet Medications Kidney disease Starvation

Protein Normal: none Proteinuria may indicate kidney disease

Glucose Normal: none May indicate Diabetes mellitus

Ketones End product of fat metabolism Normal = none May indicate: Diabetes mellitus Fasting, dieting High fat diet

Blood Normal = none May indicate: Injury Infection Menstruation Kidney disease

Bilirubin Break down product of hemoglobin Normal = none May indicate: Liver disease

Urobilinogen Bilirubin converted by intestinal bacteria Normal: small amounts May indicate: Heart, spleen, liver or hemolytic disease

Spectrophotometers Automated strip analyzer More accurate than human eye

Refrigerated samples Must be returned to room temperature

Time Follow exact time for each chemical reaction

Measuring Specific Gravity Unit 18:13

Specific Gravity Density of a substance compared to the density of water Normal: 1.005 to 1.030

Urinometer Urine in a cylinder and calibrated float is placed in urine with a spinning motion Urine collects at curved line, meniscus Read of lower part of meniscus

Refractometer One drop of urine placed on device & look through an eyepiece Calibrate with water

Preparing Urine for Microscopic Examination Unit 18:4

Urine Sediment Solid materials suspended in urine

What urine? Fresh, early morning first voided specimen preferable Examine immediately Some elements disintegrate

Centrifuge Spin ~10-15 cc of urine Solid materials settle at the bottom

Preparation Clear urine on top is poured off Leave behind 1 cc in bottom

Examine immediately Drying occurs quickly & can distort substances

lpf and hpf Low power field and high power field Indicate amount seen in a field

RBCs Normal = none May indicate: Kidney disease Bleeding in urinary tract Menstruation

WBCs Normal = small numbers May indicate: infection

Bacteria Normal: none to small amount Large amount indicates infection

Other infectious agents Fungi, yeasts Parasites

Casts Formed in kidney tubules during kidney damage Normal = none

Crystals Dependent on urine pH